feat(writers): quote default values based on SQL column type

Bun and GORM struct tags now emit quoted defaults for string/date/time/UUID
columns (e.g. default:'disconnected') and unquoted defaults for numeric and
boolean columns (e.g. default:0, default:true). Function-call expressions
such as now() or gen_random_uuid() are never quoted regardless of type.

Adds QuoteDefaultValue(value, sqlType) helper in pkg/writers and updates
both type mappers and the bun writer tests accordingly.

pkg/writers/bun/type_mapper.go

@@ -208,8 +208,8 @@ func (tm *TypeMapper) BuildBunTag(column *models.Column, table *models.Table) st
 
 	// Default value
 	if column.Default != nil {
-		// Sanitize default value to remove backticks
+		// Sanitize default value to remove backticks, then quote based on column type
-		safeDefault := writers.SanitizeStructTagValue(fmt.Sprintf("%v", column.Default))
+		safeDefault := writers.QuoteDefaultValue(writers.SanitizeStructTagValue(fmt.Sprintf("%v", column.Default)), column.Type)
 		parts = append(parts, fmt.Sprintf("default:%s", safeDefault))
 	}
 

pkg/writers/bun/writer_test.go

@@ -615,14 +615,44 @@ func TestTypeMapper_BuildBunTag(t *testing.T) {
 			want: []string{"email,", "type:varchar(255),", "nullzero,"},
 		},
 		{
-			name: "with default",
+			name: "with default string",
 			column: &models.Column{
 				Name:    "status",
 				Type:    "text",
 				NotNull: true,
 				Default: "active",
 			},
-			want: []string{"status,", "type:text,", "default:active,"},
+			want: []string{"status,", "type:text,", "default:'active',"},
+		},
+		{
+			name: "with default integer",
+			column: &models.Column{
+				Name:    "retries",
+				Type:    "integer",
+				NotNull: true,
+				Default: "0",
+			},
+			want: []string{"retries,", "type:integer,", "default:0,"},
+		},
+		{
+			name: "with default boolean",
+			column: &models.Column{
+				Name:    "active",
+				Type:    "boolean",
+				NotNull: true,
+				Default: "true",
+			},
+			want: []string{"active,", "type:boolean,", "default:true,"},
+		},
+		{
+			name: "with default function call",
+			column: &models.Column{
+				Name:    "created_at",
+				Type:    "timestamp",
+				NotNull: true,
+				Default: "now()",
+			},
+			want: []string{"created_at,", "type:timestamp,", "default:now(),"},
 		},
 		{
 			name: "auto increment with AutoIncrement flag",

pkg/writers/gorm/type_mapper.go

@@ -238,8 +238,8 @@ func (tm *TypeMapper) BuildGormTag(column *models.Column, table *models.Table) s
 
 	// Default value
 	if column.Default != nil {
-		// Sanitize default value to remove backticks
+		// Sanitize default value to remove backticks, then quote based on column type
-		safeDefault := writers.SanitizeStructTagValue(fmt.Sprintf("%v", column.Default))
+		safeDefault := writers.QuoteDefaultValue(writers.SanitizeStructTagValue(fmt.Sprintf("%v", column.Default)), column.Type)
 		parts = append(parts, fmt.Sprintf("default:%s", safeDefault))
 	}
 

pkg/writers/writer.go

@@ -81,6 +81,64 @@ func SanitizeFilename(name string) string {
 	return name
 }
 
+// QuoteDefaultValue wraps a sanitized default value in single quotes when the SQL
+// column type requires it (strings, dates, times, UUIDs, enums). Numeric types
+// (integers, floats, serials) and boolean types are left unquoted. Function-call
+// expressions such as now() or gen_random_uuid() are always left unquoted regardless
+// of type, because they contain parentheses.
+//
+// Examples (varchar):   "disconnected" → "'disconnected'"
+// Examples (boolean):   "true"         → "true"
+// Examples (bigint):    "0"            → "0"
+// Examples (timestamp): "now()"        → "now()"   (function call – never quoted)
+func QuoteDefaultValue(value, sqlType string) string {
+	// Function calls are never quoted regardless of column type.
+	if strings.Contains(value, "(") || strings.Contains(value, ")") {
+		return value
+	}
+
+	// Normalise the SQL type: lowercase, strip length/precision suffix.
+	baseType := strings.ToLower(strings.TrimSpace(sqlType))
+	if idx := strings.Index(baseType, "("); idx > 0 {
+		baseType = baseType[:idx]
+	}
+
+	// Types whose default values must NOT be quoted.
+	unquotedTypes := map[string]bool{
+		// Integer types
+		"integer":     true,
+		"int":         true,
+		"int2":        true,
+		"int4":        true,
+		"int8":        true,
+		"smallint":    true,
+		"bigint":      true,
+		"serial":      true,
+		"smallserial": true,
+		"bigserial":   true,
+		// Float / numeric types
+		"real":             true,
+		"float":            true,
+		"float4":           true,
+		"float8":           true,
+		"double precision": true,
+		"numeric":          true,
+		"decimal":          true,
+		"money":            true,
+		// Boolean
+		"boolean": true,
+		"bool":    true,
+	}
+
+	if unquotedTypes[baseType] {
+		return value
+	}
+
+	// Everything else (text, varchar, char, uuid, date, time, timestamp, json, …)
+	// is treated as a quoted literal.
+	return "'" + value + "'"
+}
+
 // SanitizeStructTagValue sanitizes a value to be safely used inside Go struct tags.
 // Go struct tags are delimited by backticks, so any backtick in the value would break the syntax.
 // This function: